/etc/systemd/system/backup.timer
[Unit]
Description=Run daily backup to Fabians NAS
[Timer]
OnCalendar=*-*-* 02:00:00
Persistent=True
Unit=backup.service
[Install]
WantedBy=timers.target
/etc/systemd/system/backup.service
[Unit]
Description=Copy files to Fabians NAS
Wants=backup.timer
[Service]
Type=oneshot
ExecStart=/root/backup.sh
User=root
[Install]
WantedBy=multi-user.target
sudo systemctl daemon-reload
sudo systemctl start backup.timer
sudo systemctl enable backup.timer
sudo systemctl list-timers --all